EP0736266A1 - Safety shoe with electrically conductive sole - Google Patents

Abstract

The safety footwear has a sock-shaped insert (23) with a watertight but water vapour permeable layer placed in the upper (13) to extend as far as the upper surface of the insole (17). An electrically conductive connection (41) links the inner side of the insert with the wearer's foot to the outer sole (21). The functional layer for the sock insert (23) is formed by micro-porous PTFE containing graphite particles for conductivity. The sole (21) is of polyurethane or rubber. The conductive adhesive is a polyurethane with graphite filling.

Description

The invention relates to a safety shoe with a shaft and a sole structure having at least one outsole and an insole connected to the shaft and which forms an electrical dissipation resistance from the footwell of the shoe to the underside of the sole structure which is within the limits of a predetermined minimum and a predetermined maximum Leakage resistance is, wherein the outsole is constructed with a plastic, which is brought by admixing electrically conductive particles to a specific resistance leading to the required discharge resistance, and wherein there is an electrical connection between the foot interior and the outsole.

For safety shoes that are worn when working in an electrical environment, such as when working with electrical and electronic devices, there are standards that require a specific electrical volume resistance range or leakage resistance range, for example in the range from 10 ⁵ KΩ to 10 ⁹ KΩ lies. On the one hand, such safety shoes must have a minimum insulation and thus a minimum leakage resistance, so that the person wearing the safety shoe is protected against harmful electric shocks when touching live devices. On the other hand, the safety shoe must also allow a certain discharge of electrical charges. If the sole structure has a very high electrical discharge resistance, so that it is practically an insulator, this acts as a dielectric of a capacitor, one electrode of which is the body of the person wearing the safety shoe and the other electrode of which is the floor on which the person stands. If the person touches live devices, this capacitor charges. If the electrical charge cannot be removed, this can have a disruptive or even damaging effect on electronic devices which the person touches after the electrical charge, and such a charge may also be harmful to the person's body. So that the electrical Charge can be reduced within a reasonable time, the electrical discharge resistance of the sole structure must therefore not exceed a maximum resistance value.

Conventional safety shoes of the type specified in the introduction have a sole made of polyurethane (PU), which has been made electrically conductive by admixing electrically conductive particles, such as carbon or graphite particles. In order to be able to discharge the electrical charge from the body after charging the body of the person wearing the safety shoe, in a known method an electrically conductive band is sewn onto the inside of a lining located above the insole. This electrically conductive band extends around the insole so that part of the band is inside the shoe and another part is under the insole and in electrical contact with the conductive PU sole.

It is also known to sew through the insole with electrically conductive threads. The electrically conductive threads then establish an electrical connection between the electrically conductive band and the PU sole and thus between the foot of the person and the conductive PU sole.

In another known method, the insole is perforated in the ball area and a vulcanized mass or plastic mass, which is made electrically conductive by adding carbon particles, is placed on the underside of the insole. In this way there is an electrical discharge through the insole to the conductive PU sole. In this case, the insole that is usually present is only a half-sole, that is, it extends in the longitudinal direction of the shoe only from the heel area to the ankle area of the foot and not below the ball of the foot.

It has become known and has proven itself to make shoes, also safety shoes, waterproof but breathable by using air- and water-permeable shaft material and the foot interior completely or partially with a waterproof, water vapor-permeable Lining functional layer, which is preferably microporous polytetrafluoroethylene (PTFE). There are such waterproof, breathable shoes in which the entire interior of the foot is lined with a functional layer, namely in that a sock-shaped insert is introduced into the interior of the foot, which has a waterproof, water vapor-permeable functional layer. Another conventional method is not to line the entire interior of the foot with such a sock-like insert, but only to line the inside of the upper surface of the shaft with a waterproof, water vapor-permeable functional layer. In shoes of this type, the upper and the functional layer, which is usually part of a lining laminate, are usually connected to one another at the upper shaft end, whereupon the lower ends of the upper and functional layer or lining laminate are then pinched around the underside of the insole. This means that the underside of upper material and functional layer or lining laminate is pulled tightly over the circumferential edge of the insole on a last under a lot of tension and the resulting gusset, that is, the area of the upper material and functional layer or lining laminate located below the insole , is glued to the underside of the insole. Due to the contour of the sole, the lasting fold can only be knocked onto the underside of the insole with strong wrinkling, which is particularly true in places with a pronounced curve, such as in particular in the toe area and in the heel area. Extreme small pleats form, especially with small shoe sizes, which have to be glazed (planed away) before an outsole is glued on. The glazing often leads to an injury to the functional layer and thus to the water leakage of the shoe at the injured point.

This problem is exacerbated in the field of safety shoes because they like to work with multi-width shoes. This means that a single shaft size is used for all shoe sizes. This leads to an exacerbation of the problem described that, in the case of small shoe sizes, extreme wrinkles form on the lasting fold, which have to be deeply glazed, which results in a high risk of functional layer injury brings with it. With the large shoe sizes, the upper material and the functional layer or the lining laminate hardly extend around the edge of the last and a waterproof bond between the functional layer and the outsole is not guaranteed.

The problems could be avoided by using a sock-like insert with a functional layer (often also called bootie) instead of a functional layer wrapped around the insole with the upper. Since the sock-like insert is not only inside the upper of the upper but also inside, i.e. on the inside of the foot of the insole, the functional layer is not at risk when glazing the gussets of the upper and there is also no risk of water leakage if this is the case with large shoe sizes Upper material only just over the edge of the last and the insole.

So far, however, no sock-like insert with functional layer material has been used in safety shoes with an electrically conductive sole structure, because the functional layer material represents a very high specific resistance, i.e. a high degree of electrical insulation. Since the sole area of the sock-shaped insert is located between the foot and the insole of the safety shoe, a discharge of an electrical charge of the person wearing the safety shoe from the functional layer is blocked.

The invention has for its object to make a safety shoe of the type specified available, which is constructed with a sock-shaped insert with functional layer material and yet allows sufficient electrical dissipation between the foot of the person wearing the safety shoe and the electrically conductive outsole.

The solution to this problem in the safety shoe of the type specified at the outset is that the upper and the upper side of the insole facing the interior have a sock-shaped insert which has a waterproof, water vapor-permeable functional layer is constructed, lined, and that an electrically conductive connection is provided from the inside of the sock-shaped insert facing the footwell to the outsole.

Due to the measures according to the invention, the high insulation resistance of the functional layer of the sock-shaped insert is bridged or overridden, so that an electrical connection between the foot of the person wearing the safety shoe and the conductive outsole is made possible.

In a preferred embodiment, the sock-shaped insert has a contact path between the foot interior and the insole at least in the ball area and the insole is constructed at least in the ball area in a manner known per se with electrically conductive material acting through the insole.

In a manner known per se, the insole can either consist entirely of electrically conductive material or only in the ball area. In the latter case, the insole in the ball of the foot area can be provided with a hole which is closed with electrically conductive material. This can either be a piece of material made of electrically conductive material attached to the edge of the insole hole, or the insole hole can also be filled with electrically conductive outsole material when an outsole is molded on.

The sock-shaped insert can either be constructed with electrically insulating material which is replaced in the entire sole area or only in the ball area by an electrically conductive material forming the contact path, or can be constructed at least in the ball area or also with electrically conductive functional layer material. In the latter case, the electrical conductivity is achieved by embedding electrically conductive particles, such as carbon or graphite particles.

There is also the possibility of building the sock-shaped insert as a whole with electrically insulating material and at least on the Places that are in the area of electrically conductive insole material can be sewn through the sock-shaped insert with electrically conductive thread. In this case, the water permeability caused by the stitching through the sock-shaped insert can be eliminated by sealing the seam, which is done at least in the area which is opposite the electrically conductive insole material by means of an electrically conductive adhesive.

The sock-shaped insert is usually sewn together from several parts to obtain the desired sock shape. The seams are then sealed on the outside of the sock-shaped insert using a waterproof sweatband. In order to maintain the electrical permeability of the sock-shaped insert, it is possible to use electrically conductive thread for at least part of these seams or for part of one of these seams and to seal at least the electrically conductive seam regions by means of electrically conductive adhesive.

An insole can be arranged on the sole area of the sock-like insert in a manner known per se on the inside facing the foot interior. This consists either at least in the ball area of electrically conductive material or it consists entirely of electrically insulating material, in which case it is designed as a half-insole that only extends from the heel area to approximately the ankle area of the foot interior.

Materials suitable for the functional layer of the sock-shaped insert include microporous stretched polytetrafluoroethylene (PTFE), as described in US Pat. Nos. 3,953,566 and 4,187,390; stretched PTFE provided with hydrophilic impregnants and / or layers as described in U.S. Patent 4,194,041; breathable polyurethane layers; or elastomers such as copolyether esters and their laminates as described in U.S. Patents 4,725,481 and 4,493,870.

If the contact path of the sock-shaped insert is to be formed by the fact that the insert itself as a whole or at least in the ball area is electrically conductive, this is achieved by embedding electrically conductive particles, such as graphite particles. In a particularly preferred embodiment of a safety shoe according to the invention, microporous PTFE filled with graphite is used for the electrically conductive functional layer of the sock-shaped insert.

Brandsohle:

Textil, Vlies oder Preßspan;
Leitfähigkeit wird durch Einlagerung von Graphitpartikeln erreicht.

Innensohle:

Textil, Vlies oder Preßspan;
Leitfähigkeit wird durch Einlagerung von Graphitpartikeln erreicht.
Leitendes Material, das einen Teil des sockenförmigen Einsatzes ersetzt: Textil oder Vlies, leitfähigkeit gemacht durch Einlagerung von Graphitpartikeln.

Laufsohle:

Polyurethan oder Gummi oder Kautschuk.

Leitfähige Fäden:

Metallfäden, z.B. aus Kupfer.

Leitfähiger Kleber:

z.B. graphitgefülltes Polyurethan.

The following materials are preferably used for the other components of the sole structure according to the invention:

Insole:

Textile, fleece or pressboard;
Conductivity is achieved by embedding graphite particles.

Insole:

Textile, fleece or pressboard;
Conductivity is achieved by embedding graphite particles.
Conductive material that replaces part of the sock-shaped insert: textile or fleece, made conductive by embedding graphite particles.

Outsole:

Polyurethane or rubber or caoutchouc.

Conductive threads:

Metal threads, for example made of copper.

Conductive adhesive:

eg graphite-filled polyurethane.

Fig. 1:

Eine erste Ausführungsform eines erfindungsgemäßen Sicherheitsschuhs mit einem sockenförmigen Einsatz, dessen Sohlenbereich aus elektrisch leitfähigem Material besteht;

Fig. 2:

eine zweite Ausführungsform eines erfindungsgemäßen Sicherheitsschuhs mit einem sockenförmigen Einsatz, der insgesamt aus elektrisch leitfähigem Material besteht;

Fig. 3:

eine dritte Ausführungsform eines erfindungsgemäßen Sicherheitsschuhs mit einem sockenförmigen Einsatz, durch dessen Fußballenbereich mit elektrisch leitendem Faden hindurchgenäht ist;

Fig. 4:

eine vierte Ausführungsform eines erfindungsgemäßen Sicherheitsschuhs, bei dem ein Teil des Fußballenbereichs des sockenförmigen Einsatzes durch ein elektrisch leitendes Material ersetzt ist.

The invention will now be explained in more detail with the aid of embodiments, with the aid of the enclosed, highly schematic, not to scale drawings. In these show:

Fig. 1:

A first embodiment of a safety shoe according to the invention with a sock-shaped insert, the sole area of which consists of electrically conductive material;

Fig. 2:

a second embodiment of a safety shoe according to the invention with a sock-shaped insert, which consists entirely of electrically conductive material;

Fig. 3:

a third embodiment of a safety shoe according to the invention with a sock-shaped insert, through the ball area of which is sewn with electrically conductive thread;

Fig. 4:

a fourth embodiment of a safety shoe according to the invention, in which a part of the ball area of the sock-shaped insert is replaced by an electrically conductive material.

In the drawings of all embodiments, the same components of the safety shoe are identified with the same reference symbols.

Although it is not very common to wear safety shoes without socks or socks on the feet, the figures show bare feet in the shoes in order to be able to see the ball of the foot in particular.

FIG. 1 shows a schematic vertical longitudinal section through a safety shoe 11 which has a shaft 13 and a sole structure 15. The sole structure 15 comprises an insole 17, on the lower peripheral region of which a lower end of the upper 13 on the sole side is glued by means of a lasting fold using an adhesive (not shown). An outsole 21 made of electrically conductive plastic is molded onto the underside of the insole 17 and onto the underside of the lasting fold 19. This consists, for example, of polyurethane (PU), which is preferably made electrically conductive by filling it with electrically conductive particles, such as with carbon particles. In the interior of the foot, i.e. on the inside of the shaft 13 facing the foot and on the top of the insole 17 facing the foot, there is a sock-shaped insert 23 which is constructed with a waterproof, water vapor-permeable functional layer, which is usually part of a multilayer laminate which is based on has a lining textile layer on the inside of the functional layer on the foot side and a reinforcing textile layer on the outside of the functional layer remote from the foot.

In the toe region there is a steel cap 24 between the shaft and the sock-shaped insert for mechanical protection of the toe region of the person wearing the shoe. This preferably applies to all embodiments of the invention.

In the preferred first embodiment of the invention shown in FIG. 1, the functional layer consists of a highly insulating plastic with such a high specific electrical resistance that a discharge of electrical charge from the foot 27 to the electrically conductive outsole 21 would be prevented through the functional layer. For this reason, the sole area or bottom 23a of the sock-shaped insert 23 is replaced by an electrically conductive material, which consists, for example, of a textile or non-woven fabric, which is made conductive by incorporating graphite particles. A shaft part 23b of the sock-shaped insert 23 consists of the insulating functional layer material, for example stretched, microporous polytetrafluoroethylene (PTFE).

In the embodiment shown in FIG. 1, the bottom 23a of the sock-shaped insert 23 with its shaft part 23b is by means of a seam 26a connected, which is waterproof sealed on the outside of the sock-shaped insert 23 by means of a sweatband 26b.

At least the ball area 41 of the insole 17 has electrical conductivity, so that there is an electrical connection between the foot 27 and the electrically conductive outsole 21 from the ball 31 via the electrically conductive bottom 23a of the sock-shaped insert 23 and via the electrically conductive ball area of the insole 17 .

On the inside of the sole area or bottom 23a of the sock-shaped insert 23 there is a half-insole 25 which does not extend over the entire length of the foot but only from the heel area to approximately the ankle area of the foot 27. The half-insole 25 consists of electrically insulating material Material so that, when extended over the ball of the foot, it would create an insulating barrier between the ball of foot 31 and the electrically conductive ball of foot 41 of insole 17.

In a modification of the embodiment shown in FIG. 1, the bottom 23a of the sock-shaped insert 23 is not replaced by electrically conductive material but is made conductive by incorporating particles made of electrically conductive material, for example graphite particles. In this case, the seam 26a and the sweatband 26b are not required.

In the second embodiment of the invention shown in FIG. 2, the entire sock-shaped insert 23 consists of electrically conductive material, preferably of microporous PTFE filled with graphite particles.

FIG. 2 shows a variant in which an insole 17 and an insole 39 are used, each of which consists of an electrically conductive material. The insole 39 can therefore be designed as a full sole.

An overall conductive insole 17 and / or an overall conductive full-insole 39 instead of an insole 17 that is only conductive in the ball area or a half-insole 39 can optionally also be used in the other embodiments of the invention considered here.

Fig. 3 shows a third embodiment of the invention, in which the sock-shaped insert 23 is constructed overall with a functional layer of highly insulating plastic with such a high specific electrical resistance that the functional layer leads to a discharge of electrical charge from the foot 27 to the electrically conductive outsole 21 is prevented. In this embodiment, this insulating barrier is overcome by sewing through the sock-shaped insert 23, preferably in the form of a zigzag seam, with an electrically conductive thread 28 at least in the ball area. This seam is sealed watertight by means of an electrically conductive adhesive (not shown).

The insole 17 is electrically conductive at least in the ball area 41 opposite the seam with the conductive thread 28.

In the embodiment shown, a half-insole 25 made of insulating material is provided.

In a modification (not shown) of the third embodiment of the invention, part of the seams or at least part of one of the seams, by means of which the sock-shaped insert 23 is sewn together from several parts, is sewn with an electrically conductive thread. At least where such an electrically conductive seam comes into contact with electrically conductive insole material, this seam is sealed by means of electrically conductive adhesive. Other areas of the seam or seams can be sealed with sweatband.

If an adhesive is used wildly for seam sealing, the flexibility of which is not particularly high in the hardened state, it is recommended to use one preferably place the seam sealed with such adhesive in the joint area.

FIG. 4 shows a fourth embodiment of the invention, in which a piece is removed from the sock-shaped insert 23 in the ball of the foot and the hole thus created is closed by means of a patch 43 made of electrically conductive material. The patch 43 is sewn to the sock-shaped insert 23, for example with a zigzag seam 44.

In the embodiment shown in FIG. 4, the insole 17 is provided with an insole hole 33. This was filled with electrically conductive outsole material when the outsole 21 was molded on. In this embodiment, the electrically conductive ball area of the insole 17 is thus simply formed by electrically conductive outsole material. The insole hole 33 has a larger diameter on all sides than the patch 43, so that the seam 44 is sealed by the outsole material filling the insole hole 33.

Claims (14)

Safety shoe (11) with a shaft (13) and a sole structure (15) which is connected to the shaft (13) and has at least one outsole (21) and an insole (17), which provides an electrical discharge resistance from the footwell of the shoe (11) forms the underside of the sole structure (15), which lies within the limits of a predetermined minimum and a predetermined maximum discharge resistance, the outsole (21) being constructed with a plastic which, by admixing electrically conductive particles, has a specific lead to the required discharge resistance Resistance is brought, and there is an electrical connection between the foot interior and the outsole (21),
characterized,
that the upper (13) and the upper side of the insole (17) facing the foot interior are lined with a sock-shaped insert (23) which is constructed with a waterproof, water vapor-permeable functional layer,
and that an electrically conductive connection (35; 41) is provided from the inside of the sock-shaped insert (23) facing the footwell to the outsole (21). Safety shoe according to claim 1,
characterized,
that the sock-shaped insert (23) has a contact path (29; 43) between the inside of the foot and the insole (17) at least in the ball area and that the insole (17) at least in the ball area with electrically conductive material (34; 41) passing through the insole (17) ) is constructed. Safety shoe according to claim 1 or 2,
characterized,
that the sock-shaped insert (23) is constructed at least in the ball area with the electrically conductive material forming the contact path. Safety shoe according to claim 3,
characterized,
that the sock-shaped insert (23) is constructed with electrically insulating material
and that in the ball of the foot a piece is removed from the sock-shaped insert (23) and the hole thus created is closed by means of a spot (43) made of electrically conductive material. Safety shoe according to claim 4,
characterized,
that the stain (43) consists of a textile or nonwoven made electrically conductive by incorporating electrically conductive material, preferably graphite particles. Safety shoe according to claim 3,
characterized,
that the sock-shaped insert (23) is constructed with a functional layer which is electrically conductive at least in the ball area by incorporating electrically conductive particles. Safety shoe according to one of the preceding claims,
characterized,
that the functional layer of the sock-shaped insert (23) is built up with microporous polyterafluoroethylene (PTFE). Safety shoe according to claim 7,
characterized,
that the microporous PTFE of the sock-shaped insert (23) is filled with conductive particles, in particular graphite particles, and therefore electrically conductive PTFE, at least in its ball area. Safety shoe according to claim 2,
characterized,
that the sock-shaped insert (23) is constructed with electrically insulating material
and that at least in the ball area with electrically conductive thread (28) is sewn through the sock-shaped insert (23). Safety shoe according to claim 9,
characterized,
that the seam created with the conductive thread (28) is a zigzag seam. Safety shoe according to claim 9 or 10,
characterized,
that the seam produced with the conductive thread (28) is watertightly sealed by means of electrically conductive adhesive. Safety shoe according to claim 11,
characterized,
that the seam created with the conductive thread (28) is arranged in the ankle area and that the insole (17) in the ankle area is electrically conductive towards the outsole (21). Safety shoe according to one of claims 9 to 11,
characterized,
that the sock-shaped insert (23) is sewn together from several sections by means of section seams
and that the seam created with the conductive thread (28) is one of the section seams. Safety shoe according to claim 13,
characterized,
that the section seams on the outside of the sock-shaped insert (23) are sealed watertight by means of a sweatband, however, that the seam created with the conductive thread is sealed with electrically conductive adhesive in the area in which it lies opposite an electrically conductive insole area.

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